NimBorg is a library for accessing Lua and Python libraries from within Nimrod code. It wraps the C API of these languages with macros which make the code far more readable than the low-level API, and also automatically handles the memory management interface of these languages so that objects aren't deallocated as long as they're accessible from your Nimrod code.
Xapian is a search engine library, scalable to collections containing hundreds of millions of documents. It's written in C++ with bindings for Perl, Python, PHP, Java, Tcl, C#, Ruby, and Lua. It is a highly adaptable toolkit that allows developers to easily add advanced indexing and search facilities to their own applications. It supports the Probabilistic Information Retrieval model and also a rich set of boolean query operators. Omega is a Web search application built upon the Xapian library. It can index a Web server's document tree (including HTML, PDF, OpenOffice, MS Word/Excel/Powerpoint/Works, WordPerfect, RTF, PS, etc.), or data exported from arbitrary sources (e.g. SQL databases).
MySQL Workbench is a cross-platform, graphical database modeling tool for MySQL. It allows you to create database models from scratch as well as by importing existing databases from SQL or DBDesigner4 models. You can then generate SQL code to CREATE databases, ALTER them, and export in various image formats and PDF/PS. Its extension system allows writing plugins and scripts in Lua, Python, and C++.
The Crate Game Engine is a game engine that is designed to make creating games trivial. The rendering and scripting engines are removed from the game engine to make the specialization of games as easy as possible. Currently, scripting support is implemented to allow a Lua script to be put directly in the game file, which can be validated as XML. Multiplayer text based adventure-style games can be played with the existing console rendering engine.